Method of manufacturing connecting rods



y 1951 w. A. PARKS ET AL. 2,553,935

METHOD OF MANUFACTURING CONNECTING RODS Filed April 17, 1948 HFFOENEVS Patented May 22, 1951 UNITED stares PATENT OFFICE METHOD OF MANUFACTURING CONNEGTIN G RODS Walter A. Parks andJames R. Parks, Milwaukee, Wis... assignors to FLA. Boucha, Milwaukee, Wis.

Application April '17, 1948, Serial No. 21,598

2 Claims. (Cl. 29-11565) Thepresent invention relates; generally, to improvements: in the art of manufactu in connect: ing rods, and relates more particularly to improvements in the construction of connecting rods having a separable capor two-piece head andto the-method of producing such rods;

It has, heretofore beencustomary practice in theproduction of two-piece connecting rods, for transmitting motion between a crankshaft and pistons of an internal combustion engine or like cases; wherein a revolvingcrank is to be connectedto a reciprocating part, to initially form therod in one piece asby forging or casting, with an elongated head havinga transverse opening therethrough, the opening being of elliptical shape or; more accurately, of a shape wherein spacedsemi-circular end portions are joined by short straight side sections. Thereafter, the rod and cap portions :are ordinarily divided by sawing across. the. head centrally between the semicircular portions of the opening therein, thereby efiectin-gremoval of the joining straight side sec tions so,that a substantially circular opening is obtained in the head, when the parts; are subsequentlyassembled, In this conventional method, it is necessary that the rod be initially formed with an elongated head to allow for the material necessarily removed by the sawing or parting operation, thereby resultingin the waste of ma terial and additional undesirable disadvantages, some of-whichare hereinafter set forth. In addition tothe wasteresulting. from the prior partoperations, such operations are costly andhazardous, requiring expensive cutting tools and precision work by skilled machinists operating; the-tools atdangerous speedsand in an atmos-.- phere laden with metallic dust particles-and chips which are. difiicult to dispose of satisfactorily ingsurface over the inner peripheral surface of theheadopening of the rod and to exercise utmostcare in machiningsuch bearing so as to provide, a perfect bearing surface.-

It'; is therefore a more specific object of our presentinvention to provide an improved method of producing a connecting rod-as a-twopiece rod.

Another specific object of this invention is tot p vide animp v d method ,ot=.qui y nde ily separating the cap from the rod proper at:

minimum cost.

An additional specific object of the present in.- vention is to provide an improved'method which.

1 requires no machining of the parts at the joint thereof tov provide for a perfect subsequent fit and proper matching and alinement of parts.

Still another specific object of the present invention is to provide an improved method of producing a two-piece connecting rod which comprises, providing a one piece blank having a head portionformed with a holetherethrough, weak-- ening the head portion along a predetermined line at which it is desired to separate the same, and thereafter applying pressure to the head portion to cause separation by fracturing along approximately the weakened line.

These and other specific objects and advantages of the present improvement will be apparent from the following detailed description A clear conception of the several features constituting our present invention,- andof the mode of constructing and of utilizing two-piece connecting rods produced in accordance with our improved method, may be had by referring to the drawing accompanying and forming a part of. this specification, wherein like reference char-- acters designate the same orsimilar parts in the several views.

Fig. 1 is a plan view of a forging or casting from which our improved connecting rod is pro duced, and illustrates the initial step of our improved method;

Fig. 2 is a similar plan view of the rod after the initial machining operations, and illustrates the second step of our method;

Fig. 3 is a corresponding plan view of the rod with the cap screws loosely applied to illustrate the third step of the method;

Fig. 4 is another plan view of the rod showing the cap separated therefrom by fracturing after application of pressure in accordance with the fourth step of the improved method;

Fig. 5 is a similar plan View of the final rod with the cap screws finally tightly applied; and

Fig. 6 is a fragmentary side'view, of the head portion of the improved and finally assembled rod.

While the invention has been shown and described herein as especially applicable to a connecting rod of a particular well-known type, wherein-the crank end or head is made in two separable parts, it is not intended or desired to. limitor restrict the scope-thereof to such specific mb diment, since the improv clameth d maya bs viously be used to produce rods of different types wherein it is desired to provide separable caps at both ends.

Referring to the drawing, the improvements are illustrated as applied to a two-piece connecting rod or pitman of conventional design comprising, in general, a shank or body portion I having a wrist pin boss I I formed integral therewith at one end thereof and provided with a bearing bushing I2, and a crank pin boss or head I3 at the opposite end, the head I3 being of two separable parts, namely, a saddle I4 formed integral with the shank I0 and a cap I5 removably secured to the saddle I4 by means of cap screws I6 or the like. The screws I6 are receivable in holes I'I bored in outwardly extending flanges or cars I8 of the cap I5 and tapped holes I9 provided in cooperating flanges or ears 20 of the saddle M; and when the cap I5 is secured to the saddle I4 by means of the screws I6, a circular crank receiving opening 2| is provided.

The rod may be readily produced in accordance with our improved method as follows: first, by forming a one piece blank as by forging or casting, the blank being provided, as shown in Fig. l, with an elongated shank or body Ill having an integral wrist pin boss I at one end and an integral crank pin boss or head I3 having integral lugs 24 and with an approximately round or cylindrical opening 2| therethrough at the opposite end; next, by machining the blank, drilling the holes II, I9, counterboring at IT and tapping at I9, boring alined transverse holes 22 through the lugs 24, inserting the bearing bushing I2 in the boss II, and machining the opening 2| in the head I3 to render the same truly circular and smooth, all as illustrated in Fig. 2, thereafter forming radial grooves 23, as by sawing, milling or grinding, transversely across the head I3 on opposite sides of the lugs 24 along the approximate desired line of separation of the cap portion I5 from the saddle portion I4, causing weakening at this point, and loosely applying the cap screws I6 in the manner shown in Fig. 3; and finally applying pressure in any suitable manner to the head I3 to cause rupture and complete separation of the cap portion I5 from the saddle portion i l by fracturing or breaking, such fracturing being caused to occur along an approximate predetermined line between the ears I8, 20 formed from the lugs 24 at the point of weakening by the grooves 23, the parts being prevented from falling apart by the loosely applied cap screws l6 as shown in Fig. 4. Thus, when the screws I6 are tightened, as shown in Figs. 5 and 6, the cap I5 will be firmly seated on the saddle I4 with the ears I8, 2%] of the cap and saddle respectively being automatically alined by matching of the broken surfaces along the line 23; and if final precision machining is desirable or necessary, such machining may be performed with the parts united as shown and maintaining a truly circular bore 2|.

While the diametrically opposite weakened zones 23 in the crank pin engaging head I3 have been shown and described herein as being formed in the connecting rod blank by a machining operation subsequent to formation of the blank by forging or casting, these weakened zones may obviously be provided in the initial blank simultaneous with the forging or casting thereof; and they may also assume diverse shapes other than the inwardly directed pointed grooves as illustrated. The circular opening 2| provided in the original forging or casting need not be truly circular, but considerable excess material should preferably be provided to permit subsequent accurate grinding and machining of the opening to truly circular formation. The lugs 24 formed integral with the head I3 should be of sufiicient size and shape to tightly and securely receive the cap screws I6 and to provide substantial and durable pairs of ears I8, 20 on the cap l5 and saddle l4 upon rupture of the head I3 along the weakened zones 23.

Prior to application of pressure to rupture the head, the connectin rod blank obviously has an integral crank pin engaging head I3 provided with a circular bore 2| and with diametrically opposite weakened portions 23, and means, such as the cap screws or bolts I6, penetrating the weakened zones 23, as through the bore I1 and tapped hole I9, for retaining the parts in assembled condition when the zones 23 are ruptured. The weakened zones 23 may be ruptured or fractured in any suitable manner, and are preferably ruptured by application of pressure with a suitable expandable device internally of the bore 2 I. Since the screws I6 remain in loosely applied condition in the holes ITI, I9 of the lugs 24 during the rupturing operation, the cap I5 isnever entirely disconnected or dismantled from the saddle I4 which is integral with the shank ID until the rod is applied to a crank pin; and there is consequently never any problem in matching the cap I5 to the proper rod. Furthermore, when the screws I6 are tightened, the rough fractured surfaces naturally interlock due to their matchingjoints, thereby causing proper alinement of the cap I5 and saddle I4 and resulting in a joint adapted to resist torque to a maximum during use. The alined, diametrically opposite, transverse holes 22 are provided primarily for lubrication purposes in actual use of the improved rod, but these holes may be formed, as shown, along the weakened zones 23, thereby aiding in the production of these zones of weakening and reducing the depth of groove necessary in such production.

From the foregoing detailed description, it will be apparent that the present invention provides an improved two-piece connecting rod which is extremely simple and durable in construction, and which may moreover be readily produced at low cost and with a minimum of operations in accordance with our improved method. Since it is unnecessary to allow forwaste material removed from the head durin the cap parting operation as in the conventional method of manufacture, the bore 2| may be made circular, or approximately so, in the original blank forging or casting and the head I3 need not be elongated, thereby eliminating or minimizing waste and reducing the size and weight of the initial blank for ease in handling, storage, shipping and the like. The rupturing or fracturing operation is simple and rapid and eliminates several of the customary hazardous and costly precision machining operations, and the improved method may be performed with a minimum amount of expensive equipment and a minimum number of skilled employees working under substantially dust-free conditions affording maximum pleasantness and health. The cap screws I6, which are preferable loosely applied to the head I3 prior to the breaking or rupturing operation, afford convenient means for retaining the parts I4, I5 in assembled condition when the zones 23 are ruptured and positively prevent the cap I5 from falling away from the main rod portion; andif desired, temporary screws may be utilized for this purpose during the rupturing operation. Since the cap I5 is never entirely removed from the rod until applied to the'crank pin, the rod may be entirely machined in one piece, thereby expediting the machining operations and assuring matching of the cap 15 with the saddle I4. The rods produced in accordance with the present method may obviously be used in the same manner as connecting rods produced in accordance with conventional methods and may be utilized for replacement purposes as Well as in new machines.

Two-piece connecting rods manufactured in accordance with the present invention have proven highly satisfactory in actual commercial use, and it has been found that the smooth internal surface of the bore 2| matches perfectly at the lines of fracture and that the joining surfaces of the cap and saddle alon the lines of fracture likewise match perfectly and seat im mediately upon tightening of the screws I6 to aline the parts. As hereinabove already set forth, the transverse holes 22 are provided primarily for lubrication purposes and also aid as a means for producing the weakened zones, and the grooves 23 may assume diverse forms and may be provided in the initial forged or cast blank.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise steps of the method herein shown and described, for various modifications within the scope of the appended claims may occur to persons skilled in the art to which this invention pertains.

. We claim:

, 1. .The method of manufacturing a connecting rod from a unitary blank having a shank and an end head provided with a cylindrical opening therethrough and with diametrically opposed lugs of narrower width than the length of said head and projecting outwardly from the opposite sides of said head, which method comprises, cutting slots transversely across and inwardly from the opposite ends of said head substantially along the aforesaid diameter to said lugs to form weakened zones, and finally applying'pressure to said head to cause rupture thereof along said weakened zones.

2. The method of manufacturing a connecting rod from a unitary blank having a shank and an end head provided with a cylindrical opening therethrough and with diametrically opposed lugs of narrower width than the length of said head and projecting outwardly from the opposite sides of said head, which method comprises, cutting slots transversely across and inwardly from the opposite ends of said head substantially along the aforesaid diameter and across the opposite sides of said lugs, and finally applying pressure to said head to cause rupture thereof along said weakened zones.

WALTER A. PARKS. JAMES R. PARKS.

REFERENCES CITED The following references are of record in the 

